This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The main objective is to determine the immunogenicity and efficacy of a novel candidate vaccine for AIDS in the macaque model. The vaccine is formulated with a novel synthetic multi-peptide conjugate (MPC) system that represents one of the major proteins of HIV known as Tat (trans activator of transcription). Tat protein has an important function in replication of the virus. Therefore, we plan to vaccinate monkeys with a synthetic MPC Tat vaccine to stimulate the monkey's immune system to produce virus specific proteins (antibodies), and white blood cells (CD4+ and CD8+ T cells). The vaccinated and unvaccinated control monkeys will be challenged with a known dose of infectious virus to determine whether the vaccine will prevent infection and or disease progression. The first AIDS cases were reported two decades ago, and WHO has recently released a report indicating that approximately 40 million persons are infected with HIV worldwide. As yet, there is no effective vaccine for prevention of infection and the epidemic continues to spread. If the proposed study is successful, it is likely to provide important information toward development of an effective vaccine for human application.